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Archive: Technical Info: 3rd Generation This forum has now been closed to replies and new posts, but can still be searched and read. Please post new threads in one of the new 3rd Gen technical Forums. Archive contains Technical discussions and questions relating to third generation (2003 - 2006) trucks.
 
 
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  #1  
Old 03-04-2004
epp1 epp1 is offline
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Location: Canton,GA
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Default 48RE Transmission problem

My accelerator will become a little sticky, and when it does my transmission will hang up in one gear and not shift until I floor the accelerator and make it shift. Also, the occurrences are unpredictable (usually after driving for 30 minutes, sit in park for 2 minutes, then the shifting will be delayed (hang in gear) for a few minutes before returning back to normal. Took it in for service and dealership could not duplicate problem; bottom line is if they do not see a code they are clueless.

Thanks in advance for any input……
  #2  
Old 03-04-2004
Oregonpharmer Oregonpharmer is offline
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Default Re: 48RE Transmission problem

The 48re is drive by wire, and has a memory that tracks your driving style and "learns" how you drive to select its shifting profile. It also does not hurt to give the linkage and switches a shot of silicone lube to keep everything loose and working.

What your problem sounds like to me is that the truck has learned an in-town stop and go driving profile. It is delaying the shifts because it thinks that is what you want. To fix it, disconnect your batteries, from the ground terminals, and let it sit a few minutes to kill the memory.

Reconnect everything and then take the truck for a drive with about 600 lbs of load in the back, and stick to the highways and out of town. It will take about 20 minutes, and the PCM will learn a new shift profile.
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  #3  
Old 03-04-2004
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TimHolt TimHolt is offline
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Default Re: 48RE Transmission problem

Oreagonpharmer, I have to respectfully disagree on the 48RE learning. However there is a trans that DC produces for the trucks called a 45RFE that does as you describe but is not avaliable in the diesel or in the 2500/3500 class. The 48RE works exactly like the 47RE and even uses the same valvebody as the 47/46REs. The throttle sticking and the symptom described sounds like the throttle pressure cable to the transmission is binding, there was a number of these trucks produced the the cable bracket on the trans was bent during assembly and binds the cable. There is also a PCM reflash for a delayed 3-4 upshift during more than a 30% throttle opening. The symptom of delayed up shifts at a take off after a hot soak surely points to the cable tho.
There is also a throttle pressure return spring on the transmission that pulls the cable back to the idle position that could have come off or binding against another component near the linkage or has been installed upsidedown to let the spring hang on the manual linkage also.
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The mods I talk about here is for information purposes only. I experiment on my own vehicles but do not endorse the modifications that I make to my vehicles to be used on others. If you use this info that I talk about, you use it at your own risk and responsibility.

03 Dodge 4X4 quad cab Dually. Two travel trailers, 1 cargo trailer. Lots of ham radios. Call sign N5ZYK Tech class. On 28.300 to 28.500 around 10:00 AM to 2:00PM every sunday.
  #4  
Old 03-04-2004
Oregonpharmer Oregonpharmer is offline
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Default Re: 48RE Transmission problem

Tim,

You may be right that it is another problem, but I have 6 of the 48re's running every day, and all have gone through this very drill when they were used for in-town deliveries before being driven on the highway. I also agree on the mechanical similarity to the 47re, but the PCM's which control the shift and throttle cutouts are very different from the pre-03 47re, which was purely a sensor based system. The newer versions have some fuzzy logic to keep from tossing the anemic OEM torque converter.

I base my response on the following, right out of the logic map instructions for the 04 PCM:

Transmission: 47RE/48RE - Automatic, Four-Speed Overdrive
Availability: 47RE - Optional with 8.0-liter V-10 and standard-output Cummins diesel engine
48RE - Optional with 8.0-liter V-10 and standard-output Cummins diesel engine
Electronic's include learned shift logic, hydraulic control, governor, overdrive, overdrive lockout, converter clutch, and fuel interrupt.
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Any comments, suggestions, or instructions offered by me only apply to off-road and non-emission regulated use. Anytime I ever used or may use reference to highway performance, it is purely as an academic reference only.
  #5  
Old 03-04-2004
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TimHolt TimHolt is offline
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Default Re: 48RE Transmission problem

Yes that is correct on the fuzzy logic system. The locgic system applies to the 3-4 shift only and convertor command timing. That was the basic fault with the delayed 3-4 delayed up shift that becomes undesirable at med/light throttles after 4 consecutive full throttle upshifts into overdrive or overload towing. The logic will change to favor full throttle and will not back down, it just hangs there. That is the reason for the reflash to lock the logic out. I had question one of the DC engineers about the explanation that had appeared in the DC print on the logic control at our last seminar. He told me that they tried to apply the 45RFE stratigie to a basicly a hydrulic controlled trans when the origanal logic system was written for the full solonoid control trans that doesnt use a govenor system, didnt work right. The reflash locks the system and works like the previous models. The 45RFE doesnt use a throttle pressure cable to adjust the shift points for example but all of the REs do and still respond to that adjustment just like a old 727. 1-2-3 shifts are governor shifts albeit electric governor but 4th and lockup are PCM direct command. In my own opinion probably the worst thing that could have been done to these units was to remove the hydrolic governor and try to mimic the same pressure with a solonoid and sensor.
__________________
The mods I talk about here is for information purposes only. I experiment on my own vehicles but do not endorse the modifications that I make to my vehicles to be used on others. If you use this info that I talk about, you use it at your own risk and responsibility.

03 Dodge 4X4 quad cab Dually. Two travel trailers, 1 cargo trailer. Lots of ham radios. Call sign N5ZYK Tech class. On 28.300 to 28.500 around 10:00 AM to 2:00PM every sunday.
  #6  
Old 03-05-2004
epp1 epp1 is offline
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Default Re: 48RE Transmission problem

Guys,
Let me add some more detail: I have had my truck hold in 2nd gear @ 2500 RPM for duration of 10 seconds. Also, it only happens when my throttle feels sticky which is only about 5% of the time. The other 95% of my driving the throttle does not feel sticky and it shifts normal. I have also had it lock into second while coming to a stop.

Thanks again for your great advice.
  #7  
Old 03-05-2004
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TimHolt TimHolt is offline
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Join Date: Oct 2003
Location: Arlington Texas (Mid cities DFW)
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Default Re: 48RE Transmission problem

epp1, dont get Oregonpharmer and I wrong, we both have the same information and both of us are on the same track, we are not argueing. The sticky throttle symptom is why I would check the cable, brackets and return spring on yours at the trans. Resetting the system considering the fuzzy logic system that just about all makes have adopted is still a good idea. This fuzzy logic system is still new and like any other software written anymore will have glitches in them. When you do the reset do the APPs reset as well. Oregonpharmer is a very knowledgeable guy, he does know his stuff, I value his input too. [img]/forum/images/%%GRAEMLIN_URL%%/laugh.gif[/img]
__________________
The mods I talk about here is for information purposes only. I experiment on my own vehicles but do not endorse the modifications that I make to my vehicles to be used on others. If you use this info that I talk about, you use it at your own risk and responsibility.

03 Dodge 4X4 quad cab Dually. Two travel trailers, 1 cargo trailer. Lots of ham radios. Call sign N5ZYK Tech class. On 28.300 to 28.500 around 10:00 AM to 2:00PM every sunday.
 

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